The Physics of Control Entropy: The Decaying Orbit

Written by
Paul Campbell, VP of AI & ML Solutions
Published on
April 6, 2026

Summary

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Building Control Systems Drift and MPC Isn’t Enough

Even the most advanced building control systems face the same reality: entropy causes performance to decay over time.

Sensors drift, equipment degrades, conditions change, and most control strategies struggle to keep up.

The Problem with Traditional MPC

Model Predictive Control (MPC) is widely used because it’s precise and model-driven, but it has a limitation:

  • It reacts within a fixed model
  • It doesn’t adapt its position, only its output
  • As real-world conditions drift, MPC loses alignment

This results in more corrections, more energy, and ultimately performance drift.

Why ILC-FD Changes the Game

Iterative Learning Control - Frequency Domain (ILC-FD) is fundamentally different:

  • It learns from past behavior over time
  • It adapts both position and response, not just output
  • It actively tracks and intercepts system drift before it compounds

Instead of reacting to entropy, ILC-FD moves with it, continuously repositioning control to stay aligned with reality.

The Metric That Matters

Control effectiveness comes down to one thing:

Can your system correct faster than it decays?

  • MPC: Holds the line… until it can’t
  • ILC-FD: Continuously repositions to extend performance

What This Means for Building Owners

  • Efficiency isn’t static, it degrades according to the law of entropy
  • MPC alone will eventually lose the fight against entropy
  • ILC-FD extends system performance by delaying and reshaping decay

You cannot win against the natural trend toward entropy, but you can use a control strategy with a natural entropy failsafe.

This is what we are developing at Facil.AI.



"...prioritizes the integrity of the system concerned over the continued operation of a once functioning control model that has since failed." -- Paul Campbell

Read the full whitepaper to learn why ILC-FD similar to Facil.AI agents is a natural solution for control entropy

Easy? Sí, Facil. Easy? Sí, Facil. Easy? Sí,

Easy? Sí, Facil. Easy? Sí, Facil. Easy? Sí,